Our country adopted cards recently, I have a card and using it almost everywhere, but I'm always carrying some cash, 200-500 bucks just in the case that card won't work for some reason. It happens. If Visa would be down, I wouldn't be disrupted and nobody would be disrupted around here. Why don't you carry some cash around, it's still a legitimate payment method and it doesn't take much space in your wallet.
That means causing some people to starve. Literally.
I can't imagine how it would improve some situation. At best, if transactions are stopped for a short enough time, you will not make it much worse.